Richard “Dic” Donohue Jr.’s brush with the Boston Marathon bombing suspects began Monday, when the MBTA Transit Police officer worked a shift at the race, a competition that his family says his great-great-grandfather once won.

Soon after twin blasts tore through the crowd of spectators, Donohue texted his younger brother, assuring him he was safe.

“Early Friday morning, as I watched what was unfolding in Cambridge and Watertown, I received no such comfort,” the younger Donohue, a patrolman for the Winchester Police Department, said Sunday as he spoke to reporters at Mount Auburn Hospital in Cambridge, where his brother is still heavily sedated and on a ventilator in intensive care. “I soon learned my brother had been shot.”

Get Fast Forward in your inbox:

Forget yesterday's news. Get what you need today in this early-morning email.

Dic Donohue, 33, was wounded early Friday morning, when he raced to help MIT and Cambridge police as they chased the Boston Marathon bombing suspects to the corner of Dexter and Laurel streets in Watertown. It is unclear whether Donohue knew then that his friend and MBTA academy classmate, Sean Collier, an MIT police officer, had been killed earlier, allegedly by the suspects he was now chasing.

A shootout ensued, during which a bullet ripped through Donohue’s right thigh, hitting both branches of the femoral artery and the femoral vein. The wound drained him of life.

“The officer’s blood volume was almost entirely lost, to the point of the heart stopping,” said Russell Nauta, chairman of surgery at Mount Auburn, said at a press conference Sunday. It took 45 minutes or so of “very aggressive effort,” he added, to get Donohue’s heart beating again.

Still, doctors said they are cautiously optimistic that Donohue, an avid runner and father of a 6-month-old son, will recover.

Though he remains in critical but stable condition, doctors and family said that on Sunday that Donohue was well enough to open his eyes, wiggle his toes, and — more importantly — squeeze his wife’s fingers.

Once Donohue is no longer sedated — probably in the next few days, if all goes well — Nauta said doctors will assess the effects of the officer’s wounds on the rest of his body. Donohue will then spend at least a week in acute care, followed by several weeks of rehab.

Speaking at the same press conference, MBTA Police Chief Paul MacMillan praised Donohue’s dedication and heroism as the officer’s teary-eyed family looked on.

“It is not uncommon for the transit police to respond to calls for assistance from other police agencies,” MacMillan said. “Last Thursday night Officer Donohue responded to just such a call for assistance from the MIT and Cambridge police departments. We expect he had no idea that his classmate and friend had been involved. He was doing his job.”

Edward Donohue said he and his relatives understand Dic Donohue’s actions. The family includes several veterans and public servants.

“As a brother, a fellow officer, and as an American, I cannot describe the pride I have at how Dic, other officers, and emergency personnel acted early Friday morning,” he said. “With complete disregard to their own safety, officers withstood a barrage of gunfire and explosives more reminiscent of a war zone than a quiet suburban street.”

Donohue’s family said they have a bright outlook about his recovery, even joking Sunday about how Donohue will probably bask in the limelight once he is out of the hospital.

“I’ll always tell him, ‘You’re never going to see any action because you’re on the subway.’ But there he is jumping into the midst of a gunfight in Watertown and making Transit very proud, and making our entire family, and I assume our entire state and country, very proud,” Edward Donohue said. “He’ll be eating this up, you know and we actually joked about that. His wife said he’ll never live this down; he’ll never have to make himself another sandwich.”

Even as his family stays by his bedside, friends and neighbors are also pulling for Donohue, who did a stint in the Navy, studied abroad in Ireland, and worked at the Omni Park House hotel before joining the MBTA police force.

Following news that he had been shot, neighbors on his Woburn street lined their yards with mini American flags. And at the Virginia Military Institute, which Donohue attended, cadets signed a flag with well wishes for him.

Jake Copty, who attended the military college with Donohue but had only kept in touch sporadically, recalled his old friend as a “laid-back cadet with a wicked sense of humor,” and a deep enjoyment of life.

“The only rule we didn’t break was the honor code,” Copty wrote in a message to the Globe, adding that when he learned of Donohue’s shooting, he was horrified but not surprised.

“Dic serves his community and risks his life to help people,” Copty wrote.

BostonGlobe.com complimentary digital access has been provided to you, without a subscription, for free starting today and ending in 14 days. After the free trial period, your free BostonGlobe.com digital access will stop immediately unless you sign up for BostonGlobe.com digital subscription. Current print and digital subscribers are not eligible for the free trial.

Thanks & Welcome to Globe.com

You now have unlimited access for the next two weeks.

BostonGlobe.com complimentary digital access has been provided to you, without a subscription, for free starting today and ending in 14 days. After the free trial period, your free BostonGlobe.com digital access will stop immediately unless you sign up for BostonGlobe.com digital subscription. Current print and digital subscribers are not eligible for the free trial.